If you have a specific bug and you've identified the Oracle patch number that fixes the bug, you'd be tempted to just download the patch from Oracle.
According to SAP, you should not download any patches from Oracle directly. As you know, the Oracle binaries themselves are slightly different for an SAP system.
Instead, if you have the Oracle patch number, search through the README files that come as part of the SAP Bundle Patch (SBP) for Oracle downloads located on the marketplace: http://service.sap.com/oracle-download to see if the Oracle patch is included in the bundle patch.
If you can't see it in there, then it may be worth asking SAP to clarify if/when they may include it in the next bundle patch.
Each bundle patch is released monthly, but it may not mean that relevant Oracle patches older than a month are included in the bundle.
The bundle patches themselves are cumulative, so you only need to apply the latest one. It includes specific Oracle patches, plus a CPU patch (dependent on the date/time of the released SBP).
Remember to re-check the SAP notes about Oracle database parameters after applying SBPs, since SAP usually update the notes at each SBP release, to include any relevant _fix_control or event parameter settings.