Searching in Custom Module

I've created a custom module that contains the following fields:

Created Time
DateTime
Last Activity Time
DateTime
Modified Time
DateTime
SIC Code
Single Line
SIC Code Owner
Lookup
SIC Name
Single Line (Unique)

When I access this module from the lookup field in the Leads module that I created it only allows me to search based on SIC Code. Is there any way to make it search also based on SIC Name?

Created Time	DateTime
Last Activity Time	DateTime
Modified Time	DateTime
SIC Code	Single Line
SIC Code Owner	Lookup
SIC Name	Single Line (Unique)