So, in my last post I was asking how to build a dynamic search filter using LINQ and EF4 (See Here) and finally came up with the solution of building the expression as a str
Have you looked at the Dynamic LinQ Library: http://weblogs.asp.net/scottgu/archive/2008/01/07/dynamic-linq-part-1-using-the-linq-dynamic-query-library.aspx
And for your question How to use "contains" or "like" in a dynamic linq query?
Previously I have gotten the code for this lib and just taken a look inside, it is pretty easy to follow.