Question: Search from , text fields

I'm building a search form where users can search for people by zip code. Trying to get an opinion here. Well maybe more then just one. Should I have seperate textfields, say (arbitrary) 3 , where they can put in 1 zip code per field. Or do I do it with one text field , using delimited entries - i.e 20199, 20294, 20599, 20054 Or the one text field with boolean. i.e 20199 AND 20294 OR 20599 I'm thinking boolean is the best, but being the inexperienced lame brain I am , how difficult will it be ? by the way, this will be seraching a database field(s) Alright I await the wisdom of PHP-General Thank you , Stuart