This is just a wild idea. (I'm posting while pondering a solution for an XSL problem I'm stuck on so forgive my lack of focus.) If you can somehow tokenize the search criteria splitting it on white space and build a list of
string nodes then you might get away with something like this:
The example assumes that you have already defined a template that will turn a space delimited string into an XML fragment such like: <elem>credit</elem><elem>card</elem>
The template would have to be a recursive function of course.