The Oracle client is required software if you wish to access an Oracle database.
To download oracle client choose the Oracle version (8i/9i/10g/11) and select the Oracle release for Operating system that you want to download and it will take you to next page, where you will find the Oracle client.
Oracle Instant Client:
Instant Client allows you to run your applications without installing the standard Oracle client or having an ORACLE_HOME
Click here to download Oracle Instant Client for all O/S platforms.
For more information on Instant Client, see the official Instant Client site
Please see the Oracle Instant Client discussion forum for any questions/issues.