It depends on your position, his position, the size of his 3-bet, the effective stack depth and exactly how loose, you think, he is 3-betting. You should also have a 4-betting range, so you need to first determine, if your hand is good enough to continue, and then if it play better as a call or a 4-bet.
I know, this is not the simple answer, you are looking for, but poker is not that simple. There are for sure hand range charts somewhere, that can give a general answer, but if you really want to work on this and perfect your ranges, you need to get programs like solvers or PokerSnowie and put in some hours away from the table.
In general though you should tend to fold hands, that mostly make a second best pair. A hand like KQo might look like, its to good to fold, but the issue is, that even when you flop relatively strong, your situation often just got worse. Flop come KXX, he have AA or AK, there goes a lot of money. Flop comes QXX, he have AA, KK or AQ, there goes a lot of money.
So if I have to outline some kind of general range, completing ignoring positions, stack size, bet size and player tendencies, maybe you want to continue against a 3-bet out of position with something like 88+, AQ+ and some suited connected hands.