store key name pattern search

Hi

I have the following case

select * from foo;
col1
---------------------------------------------------------------------------------
"show_id"=>"1", "group_id"=>"32", "group_name"=>"slb", "group_add_by"=>"557651"
"show_id"=>"2", "group_id"=>"33", "group_name"=>"slc", "item_add_by"=>"557652"
(2 rows)

Is there anyway I can do a pattern search by hstore key name something like

select * from foo where skeys(col1) like '%add_by%';

I looked on the doc but did not see anything , or did I miss it ?

Thanks

Armand