A capital loss cannot be used to offset income from other passive activities.
The income from a partnership is "pass-through" income, reported on your tax return exactly as it would be if you had earned it on your own. Capital gains can't be used to offset rental losses, and rental income can't be used to offset capital losses.
When you sell the partnership, you will be able to recoup any remaining losses. Until then, you're stuck. Unless, of course, you invest on your own and have a gain. Then you can deduct your capital losses from your gains, and deduct another $3,000 in losses in addition.
