Seems like a library mismatch here: Your application tries to load the lib in /b/32_216/rdbms/lib/libclntsh.dylib.10.1, but you state that you have instant client installed in /usr/local/oracle/instantclient_10_2. You should stick to either one, I'm not sure whether libclntsh.dylib.10.1 of these two installations are compatible. I recommend building and running both the Qt OCI plugin and your application against the instant client.
Then there's a second problem: The oracle instant client is built as x86 32 bit binary only. Please check the output of
lipo -info /usr/local/Oracle/instantclient_10_2/libclntsh.dylib.10.1
Most probably you get
Non-fat file: /usr/local/Oracle/instantclient_10_2/libclntsh.dylib.10.1 is architecture: i386
In that case, make sure to build your Qt application only as 32bit X86 application. To ensure this add this to your .pro file:
CONFIG -= x86_64 ppc64 ppc
CONFIG *= i386
If you use a precompiled Qt library, then you're lost at this point, as those only contain X86 64 bit code. You must build Qt manually in this case.
Last, please show the conetents of your DYLD_LIBRARY_PATH - you did not mention