Install lxsplit (~hjsplit on windows)

sudo apt-get install build-essential
wget http://www.freebyte.com/download/lxsplit.tar.gz
tar -xvvzf lxsplit.tar.gz
cd lxsplit-0.1.1
sudo make
sudo make install

To split a file in files of 15 MB:
lxsplit -s FILENAME.EXT 15M

to join files:
lxsplit -j FILENAME.EXT.001