I want to export the file system which consist of several partition. For example I export / and there are /home, /usr
partitions. On client side I can see all files in /, but /home and /usr are empty.
So far I failed to find the way to make other partitions visible in one mount. 
Of course I can make additional mount points and mount them separately.
What are this magic options to do it?
There is no magic, you can export single mountpoint without submounts , otherwise you will have collisions on inode level
Well, I had very old server running 2.2 kernel and on that system I could see other submounts. It was my guess that it should be possible with new nfs too and defaults are only changed.