Queries :: Using OnClick In Expression Builder?

I have query that filters my list in Access. The list can be filtered in different ways(like using a combobox). This is the criteria of the query for the field Title of the table Book:

Code:
Like IIf([Forms]![frmName]![cmbSearch].[OnClick];"*" & [Forms]![frmName]![txtSearchBar] & "*"; [Book]![Title])

What I want is when the cmbSearch is clicked, the list must show the Tiltes where the title of the book contains the words of the search bar. When its not clicked on that button, the list must show all the titles.

Here is the SQL of the query:

Code:
SELECT Book.ID, Book.Title FROM Book
WHERE (((Book.Title) Like IIf([Forms]![frmName]![cmbSearch].[OnClick],"*" & [Forms]![frmName]![txtSearchBar] & "*", [Book]![Title]))

The problem is the list filters whether I click on a different cmdButton or an optionButton. I dont know why [cmbSearch].[OnClick] doesnt work.