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 "instantclient_12_1".
3. Set the library loading path LD_LIBRARY_PATH in your environment to the directory in Step 2 ("instantclient_12_1").
4. Start your application.