You cannot open 5.7z.016 by itself. It is useless without the preceding files ( .001 through .015 ).
The .016 file is the 16th chunk of this split archive. 5.7z.016
Right-click only the first file ( 5.7z.001 or sometimes a master file if provided) and select "Extract Here" using the 7-Zip software . You cannot open 5