index on search - pg 9.2

Hi guys

I've got a query that is doing a search with wildcards:

> OR (description LIKE '%change%')

Query: - Taking > 14 secs to run

> SELECT j.id, ff.gtime
> FROM public.status AS s
> JOIN public.job AS j ON j.status_label_id = s.id AND j.clientid = 3369
> JOIN public.log AS ff ON ff.jobid = j.id
> AND ff.clientid = 3369
> AND (ff.description LIKE '%change%')
> ORDER BY gtime DESC
> LIMIT 100

Explain analyze: https://explain.depesz.com/s/1OLW

I'm using PG 9.2 and, read about gin indexes.
I've created the index to test, but the query is not using it.

> create index on log gin (description gin_trgm_ops)

Can you guys help to improve that part please?

Patrick.