HttpClient & SOAP (C#)

I'm trying to use the HttpClient class to send a SOAP message:

Doing so with REST seems easy (code from here) :

using System;
using System.Net.Http;
using System.Json;

namespace ConsoleApplication39
{
class Program
{
static void Main(string[] args)
{

HttpClient proxy = new HttpClient();
proxy.GetAsync("http://localhost:14892/api/Bloggers").ContinueWith((r) =>
{
HttpResponseMessage response = r.Result;
response.Content.ReadAsAsync<JsonArray>().ContinueWith(
(a)=>
{
foreach(var w in a.Result)
{
Console.WriteLine(w.ValueOrDefault("Name").ToString());
Console.WriteLine(w.ValueOrDefault("Intrest").ToString());
}
});

});

Console.ReadKey(true);

}

}
}

I would like to do something similar with SOAP.

I have the host (http://opensearch.addi.dk/2.2/) and the SOAP message to POST:

<?xml version="1.0" encoding="UTF-8"?>
<SOAP-ENV:Envelope xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/" xmlns:ns1="http://oss.dbc.dk/ns/opensearch">
  <SOAP-ENV:Body>
    <ns1:searchRequest>
      <ns1:query>dc.title=zorro AND dc.type=bog</ns1:query>
      <ns1:agency>100200</ns1:agency>
      <ns1:profile>test</ns1:profile>
      <ns1:start>1</ns1:start>
      <ns1:stepValue>10</ns1:stepValue>
    </ns1:searchRequest>
  </SOAP-ENV:Body>
</SOAP-ENV:Envelope>

... but how to send it ?

I'll admit that this is the first SOAP Web Service I have ever used so I may have no idea what I'm doing, but in its simplest form could it be something like :

HttpClient hc = new HttpClient();
hc.BaseAddress = new Uri