Where can I find Warframe parts for the newest update?

Solution 1:

The drop system has changed a bit, you no longer have "void keys". Now you have void relics, and void fissures.

A relic is like a void key, in the way that it gives a set of specific items as a reward.

The big difference here is that the relic can be refined to increase the odds of getting a rare drop, at the cost of spending void traces.

A void fissure is a mission in which you can equip a void relic and open it (When acquiring the 10 reactants required), and can give void traces among its rewards.

Once the relic is open and the mission complete, every member of the squad will get their own reward from their own relic, but they can choose to swap and get a copy from other players reward.

I dont know which warframe are you trying to farm but you can get that info from the wikia. Also, you can see where to farm the required relic in the previous "Void Relic" link, under the section "Drop Location".

Good luck with that farming!