How can I fix a hole in a 100% polyester karting race suit?

My son has torn a hole in his karting race suit, that he uses when it is a wet race. It now leaks & makes him very wet!! How can I mend it please? Or where can I buy a patch & fix it please?
The make is TUZO & it says on the label motercycle clothing. The outer shell is 100% polyester & it has a softer lining which is also 100% polyester.
Kind regards
Joanne, November 2015