HAProxy, how add variable “dst” (IP client) to option httpchk GET line

I have memcached cluster with couchbase. For balancing using HAProxy. But have problem with check health.

For check is good following request:

curl -v http://10.0.110.1:8091/pools/default/buckets/default/nodes/10.0.110.1%3A8091/stats

Response is 200 or 404.

In HAProxy:

option httpchk GET /pools/default/buckets/default/nodes/10.0.110.1%3A8091/stats
  server memcached1 10.0.110.1:11211 check inter 3s port 8091
  server memcached2 10.0.110.2:11211 check inter 3s port 8091
  server memcached3 10.0.110.3:11211 check inter 3s port 8091

Problem with "/pools/default/buckets/default/nodes/10.0.110.1%3A8091/stats". How add variable IP of hosts.

Maybe use a variable "dst". But did not work for me:

option httpchk GET /pools/default/buckets/default/nodes/%25%5Bdst%5D%3A8091/stats

Please help me with this issue.