Create lookup filter based on contains filter

Hello, friends

DOes anyone have experience in creating field lookup filter based on its contains value not on the first characters. For example, I have organization number 40003740302 and i would like to find the record by typing 0302 not 400037. Its usefull because in our country all organization numbers start with 4000 so its not much use. I found similar problem on this link but it doesnt provide any code sample. Usage of wildcard * would not be solution too (customer requirements). Do you have any experience in solving such a problem. It would be nice if you could help me.

Best regards,