Access 2010 - How would you pass the returned result from an if statement to set field criteria that contains logical operators

Access 2010 - How would you pass the returned result from an if statement
to set field criteria that contains logical operators

Im looking to set field criteria with an if statement but the result of
the if statement will contain a logical opertor.
eg
If([Code]="PEN", "GENR", "GENR OR GENR-R")
The result is that for a given row the expression would set the criteria
to GENR if column Code = PEN and if Code <> PEN then the criteria would be
GENR OR GENR-R
Your help is greatly appreciated. thanks