I assume it's possible but I have no real idea how to do it.
My best guess is that you'll be using Client Side Java Script for this.
I would THINK there might be a way to take your search term and get that into a scoped variable. Then if there was a dojo or jQuery tool that could find text and wrap it in a span tag, maybe it could be done. If there was a tool you'd feed it the scoped variable for the search term.
Just a thought..