Not sure if you have already seen the following link
but I believe you should be able to do at least part of your containment with the "filter" parameter.
Sorry for not replying earlier but I should have been more specific. That filter parameter is the one I'm referring to. It only allows the equals parameter. If it allowed a containment operator, developers could create more intelligent name-search functions. e.i 4 employees whos full name contains the first name 'Antonio'
See my meaning?