This guide aims to help you on how to configure a clean and lightweight Oracle Client with .NET Framework. This guide is intended for legacy applications that are bound with classic Oracle.DataAccess. It is recommended to move on to Oracle.ManagedDataAccess.
32 bits version
http://www.oracle.com/technetwork/database/windows/downloads/utilsoft-087491.html
ODAC 11.2 Release 6 (11.2.0.4.0) [Released January 14, 2014]
64 bits version
http://www.oracle.com/technetwork/database/windows/downloads/index-090165.html