Only 18.104.22.168 or higher is certified on windows 2012.
You can download it from MOS patch 13390677
This is a complete installation set.No need to install the base release.You need to download the first two zip files for RDBMS(refer READ ME)
Oracle 11gR2 - 22.214.171.124.0 to 126.96.36.199.0 is Not Certified / Supported on Microsoft Windows Server 2012 R2
Only Oracle Database 12c (188.8.131.52 and higher is Planned to be Certified on Microsoft Windows Server 2012 R2