What do you call someone who has a 'problem' [closed]

As others have noted, I don't think there's a single word that covers all cases. It depends on the type of problem.

Often you use a word that describes the person's relationship to you regardless of the fact that they have a problem. Like if it's a customer complaining about bad service or defective products, you generally just call them the "customer". If it's a user of a computer system they are "the user". Etc.

If the problem has reached the point where the person is bringing a lawsuit, they are "the plaintiff".

If it's a medical problem: "patient". Occassionally, "the afflicted".

If the person is making a complaint, you can call them the "complainant", but I think that's pretty rare.

If the problem is caused by someone else and you want to place blame, you can say "the victim". That isn't necessarily limited to a crime, like you can say "the victim in the automobile accident".

The term for 'person with a problem' is probably person, though you might try sufferer. I imagine, however, you want to cut it down; for example, a person who has asked you to solve the problem might be the applicant, questioner or (technically correct though little used) querent.

I don't know a word the matches in general.

But in some contexts you can describe him with words that fits the situation. For instance:

If the problem faces him to a challenge you can call him challenger or contender.

If the situation is very unlucky for him you can call him unlucky fellow.

A little bit more general term may be:

• person affected
• person concerned

If the person has brought their problem to your attention they could be called the complainant.

If they are suffering under a problem, they could be called the sufferer (as @TimLymington explained) or the victim (if it wasn't their fault).