I need to search within a site which has many filters like list names..probabily it will have 5 filters..After clicking search button it needs to find matching keyword and also does filtering..For this situation i can use existing search in sharepoint or have to create custom search using webparts..
In the webpart properties of the Search Core Results webpart filters can be set in the 'Results Query Options' section. You can add filters in the 'Append Text To Query' textbox. For example to return only documents, items based on a certain ContentType or you can set a scope. If this is what you need you can use the ootb Search Core Results webpart.