Yes, Im looking for a boyfriend who is honest more or less means the speaker is trying to find honesty in a boyfriend. Language is full of often quite subtle metaphor, or rather, slight extensions of basic meanings to cover somewhat more extended ones. But like I say, I dont think the person as location or container is too much of a stretch of/for in.
As a dialogue:
A: What qualities/things are you looking for in a boyfriend?
B: Honesty. A short answer might beat the repeating of looking for and a boyfriend in Im looking for a boyfriend who is honest.