Function based indexes and or expansion.

OR expansion hint to do FFS instead of FTS

I won't reinvent the wheel, this post covers the issue:
https://dioncho.wordpress.com/2009/07/31/function-based-index-and-or-expansion/
There are different options, based on database version, index type and edition.

Or expansion cannot use function based indexes in 11.2 and below.

Related notes:

11.2 Bug 17650872 : WRONG RESULTS RUNNING QUERY WITH OR-EXPANSION AND FUNCTION BASED INDEX

Or expansion not supported with function based indexes in 11.2 and below. 
https://support.oracle.com/epmos/faces/DocumentDisplay?id=281483.1&displayIndex=8#REF