Getting result from EXECUTE

I have a trigger function that I want to apply to several tables, hence
my use of TG_RELNAME. I just want the record to get inserted if an
UPDATE comes from my view rule if the record for the client doesn't
already exist. This is what I have, but I'm finding the FOUND is not
returned for EXECUTE. How can I accomplish what I need?

CREATE OR REPLACE FUNCTION "public"."create_fldclientnumber_trigg_func" () RETURNS trigger AS'
begin
EXECUTE ''SELECT * FROM '' || TG_RELNAME || '' WHERE fldclientnumber = '' || NEW.fldclientnumber;
IF NOT FOUND THEN
EXECUTE ''INSERT INTO '' || TG_RELNAME || '' (fldclientnumber) VALUES ('' || NEW.fldclientnumber || '')'';
END IF;
RETURN NEW;
end;
'LANGUAGE 'plpgsql' VOLATILE CALLED ON NULL INPUT SECURITY INVOKER;

Thanks for the help.

--
Robert