Add custom fields under All categories in search sidebar

[Nuwan2014]

Hi 

http://www.phonebank.lk/search

this is my site search page...when user clicks "See all listings" in home page they direct to the search page.

default redirection is to "All categories" and it doesn't show the custom fields...but if you click on a sub-category(For sell) it shows custom fields...

How can I make available those custom fields under "All categories" or if it is not possible how can I redirect users to a sub-category(For Sell) when they click on "See all listings" in home page

Thank you very much
Nuwan