To get rid of the odor (including the odor that the cats can smell but people can't), I would recommend Feline Odor Neutralizer (F.O.N.). I get it from Amazon. It doesn't have an odor of its own, but its enzymes work on the odors that cats leave behind.
I find FON works most reliably for clothing if I spray the clothing and then bag it up in plastic for up to 24 hours before washing. (I have found that simply washing and drying clothing normally is not enough to get rid of all the cat odors.)
If your mattress is not covered with a water-impermiable mattress cover, you may need to treat the mattress also. In this case you have to pour enough of the liquid on the spot to ensure that it will reach all areas the orignal urine reached. Cover with saran or plastic for up to 24 hours, then put a fan on the mattress to dry it out as quickly as possible (to prevent mold).