Ok I'm an expert on this one from raising cats
FIRST OFF... It's the SPRAY and not the pee that really STINKS. You need to FIND where the spray spots are. usually up a table leg or on a box or someting like that. SORRRY.. but you will have to get on all fours and smell EVERYTHING to find SOURCES. if you don't get exact spray sources you will NEVER get the smell gone NEVER.
Get a product called ODORMUTE. Mix it way stronger then directions say!!!! Let it SOAK in the spot for awhile and then SCRUB and then let it dry and DO IT AGAIN the next day. then after that dry's .......do regular cleaning with a pet carpet cleaner and vinegar..
If the smell is in something like a BOX or something VERY POROUS....THROW IT AWAY... you will never get the stench out.