WORKAROUND
1. Download the msi installer here

2. Once the zip file has been downloaded
3. Open the zip file with the File Explorer (Windows Explorer in Windows 7) and extract the .msi file. For example:
The zip file contains these files

Note : The msi file can be executed with a double click, if it doesn't work, try step #4.
4. Open a Command prompt as Administrator
5. Run the msi installer from there, in this case, enter the full filename with the extension, see image below:

Keep in mind, the 64-bit version of Toad for Oracle will need a 64-bit Oracle client. Basically the bitness must match between Toad for Oracle and the Oracle client.