I thought I read a book somewhere in Skyrim that stated that there's no real documented info as to whether Khajiit and Argonians can breed with men or mer, but it doesn't state they can't.
I believe it has been explicitly stated as their biology is simply too different, I could be wrong though and I can't for the life of me remember a credible source. So take it with a grain of salt. The reason there's little info (In world) is because men and mer rarely have relations with the beast races.
On a somewhat related note, I just read through every volume of The Real Barenziah, there's a passage in there that explains why any woman wanting to get with a male Khajiit should think twice.