Use a layout in List View and place the search fields in the Header.
That's my first choice. Other options that you can use:
Use a tab control and place the search fields inside a tab in the tab control.
Use a button to perform a script that uses New Window to open up a small floating window to display the search fields.
In all of these situations, I define global fields to use as the search fields as it is then easy to write a script that uses the criteria entered by the user into the global fields to perform the find.