Matching value inside a lookup with wildcard?

[zewashere]

Hello, i'm new to Splunk and i need some advices.

I've created a lookup named my_color_lookup, with 2 column :

color,danger

red,high

yellow,medium

green,low

Then my base search is :

sourctype=foo AND customer_id=520.

This search returns me a quantity of event and has several fields. One of these fields is src_light.

I want to create a new field "risk_level" in my event

if src_light match with one color inside my lookup, i want my search to

- add a value low or medium or high in the new field risk_level, 

- leave the field risk_level if ther's no matching.

Thanks for your help and suggestions

[zewashere]

one last things, i need to use wildcards for the search... the field src_light can have value like "dark yellow" or "deep red" and these colors need to match.