altering the query used in wp admin reports

hi

I have a custom post type customers that I’ve added a meta field too (customer type).

On the customers report (in wp-admin), I’ll like to be able to search by customer type ( in standard search box).

e.g. I might put ‘retailer’ into the search box

What I’d like to know is there a hook I can use to hook into that query ? to tell it to search by customer_type also