Space in a search is an implicit “AND”. So you should already be able to narrow a search to things that only contain both X and Y. By using a search X Y or narrowed even further "X" "Y". Some examples of your search syntax would help.
(I think I’ve also said that before, and been confused about how it actually works. But I keep testing it, and it seems to work.)
Also please search before posting in FR. Related existing threads. (I’m sure there are a couple more. This has come up in help threads quite a few times.)