Restriction of search parameter in web ui

Hi All,

I have created 2 parameter in search view that is "Material" & "Description" and it is working fine with result. Now my client requirement is to restrict search criteria like user should input at least 3 character excluding '*' in any of the parameter and user should input either Material or description at a time not both.

Please suggest step by step procedure with code to achieve the same.

regards

Nittu