In the query criteria row of the field for the table that has the entire record put Like "*" & [fieldname] & "*" where fieldname is the name of the field where only part of the value is entered. You should not need to add AND <> NULL to that if the join between your tables is a inner join since NULL would not be LIKE any value in the table which has the partial number. I presume you know how to create a query and join the two tables.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.