There is no patch that will ever make Lightroom 3 read NEF files from that camera. The camera was introduced after support for Lightroom 3 ended. But you can use the newest DNG converter to create digital negative (DNG) copies of your raw images, and they can be opened using Lightroom 3. But I can tell you that you would be much happier if you had Lightroom 5. It has direct support for your camera, and a much improved process version.
Thank you Jim......
LR 5 is in the works for me, but I'm in the middle of editing a wedding....my second shooter had an 800 and so I'm just wanting to finish up before I get LR5! I'll look for the DNG converter.
Careful - the Adobe text says LR 5.2 RC expires at the end of September, so you'll need another version then. Also, LR5.x catalogues can't be read by LR3.x (or LR4.x, or anything earlier), so there's no going back.
Let's be clear about that. Lightroom 5.2 RC will upgrade the older catalog, but it does that by creating a copy of the original. The older version of Lightroom, and the catalog which it uses, remain intact and completely usable. The only thing that would become confusing in this situation would be trying to use both versions. You would most likely see different interpretations.
Fair point SImon - but I get the sense that the OP's prime interest is in getting the second shooter's files converted rather than converted and catalogued, and 5.2 RC is a viable stop-gap for that purpose.