selecting rows from table under public schema where each row acts as a schema

in My DB,I have customer table in public schema.And then I have schema named after each customer.Each customer schema contains different tables like portals,plugin.... .When I want to select portals used by customer 'a '.I can do select * from a.portal. Now I want to select all the customers having particular 'portal' info.But portal table is specific to each customer(a.portal).So How should I query to 'postgres' in this situation.