Dealing with point and click harass
First, what you call "point & click abilities" are usually refered to as "targeted abilities".
I see four ways to deal with this kind of harrassing champions. Depending on who you are exactly facing, some methods are better than others.
Out-range them. Targeted abilities typically have shorter range than true "skillshots" (non-targeted abilities), e.g. Ezreal's Mystic Shot or Nidalee's spears. If you choose this approach, stay within the range where you can hit your enemy, but he can't hit you. For example, Ryze is very weak against Cassiopeia for this specific reason.
Out-sustain them. Some champions have very efficient regenerative abilities, e.g. Warwick, Vladimir, or more recently Aatrox. These champions can't be killed simply by being harassed. Let them waste their mana on you while you keep recovering from your wounds. Zilean can't heal himself, so eventually he will have to go back to his base before you do.
Shield against their attacks. Champions like Shen are great against harassing abilities, especially if you can easily foresee when you will take damage, because your shield will absorb most of the damage taken. This is, is my opinion, Zilean's greatest weakness.
Attempt to crush them. This is the high risk-high reward method. Champions such as Talon (melee assassins with a gap-closing ability) are efficient against squishy targets, because their full combo deals a scary amount of damage. When the enemy moves towards you to harass, analyze the situation. If you think it favors you (= the enemy jungler is far enough, your opponent is not under his tower, there are enough allied minions and not too many enemy minions), dash in, yell at your monitor and give him everything you have. In some cases, you will even be able to dive under his tower, kill him (unless he is actually Zilean and had his ultimate, of course), and survive.
However, remember that your choice must not only be aimed at the laning phase, but the whole game. For example, don't pick Shen for the mid lane if your team expects heavy burst damage from you later on.
I'm going to use Orianna as an example, because that is who you mentioned, but much as Fizz is in a subset of champions, Orianna is as well.
This subset has strong ZONING abilities. Orianna can zone with her ball extrememly well. You should be placing the ball in strategic locations, forcing Zilean to go near it in order to bomb you, when he does, you can then Command:Dissonance (W) him for major damage AND a slow. The slow should allow you to get off at least an auto-attack if not two or three in addition to the (W), and if you have the mana, no reason not to follow up with a Q as well. Assuming you itemize correctly, you should have PLENTY of mana to do this. Orianna is much more mana efficient than Zilean, especially if he is constantly rewinding to double bomb you. If your properly trading with Zilean you'll find you do more damage than he does.
The range of Zilean's Time Bomb is 700, and the range of Oriana's Command: Attack is 825. You should be able to poke Zilean a few times without taking harass back, forcing him to play more conservatively. This will largely depend on your ability to position her ball.
Also watch for Zilean to use two bombs in a row (meaning he's used Rewind). This should provide another window of opportunity for counter-attacking, as his only available skill is Time Warp.