Note: Instant Client 12.2 is now available and is recommended for all environments.
Download it from here.
1. Download the appropriate Instant Client packages. All installations require the Basic or Basic Light package.
2. Unzip the packages into a single directory such as "C:\instantclient_12_1".
3. Append the directory "C:\instantclient_12_1" to the PATH variable in the "System variables" section of the Environment Variables pane. On Windows 8 this can be accessed by navigating to Control Panel>System>Advanced System Settings>Environment Variables.
4. Start your application.