Http GET request to Apache solr with umlauts from node.js

I'm trying to make request with umlauts in URL parameters to get recommendations:

function getRecommendations(auth, callback) {

    var params = '+"olivenöl"';
    var host = 'something.com';
    var path = "/solr/cloud/select?q=*&fq=ingredient_t:(" + params + ")";

    var options = {
        "host": host,
        "path": path,
        "method": 'GET',
        "headers": {
            "Authorization": auth,
            "Content-Type": "application/json",
            "Accept": "application/json",
        }
    };

    http.request(options, function (res) {
        res.setEncoding('utf8');
        var body = '';

        res.on('data', function (d) {
            body += d;
        });

        res.on('end', function () {
            callback(body);
        });

    });
}

Response has empty list of recommendations in a case if German umlauts present in URL params.

I tried to encode as ö => oe or ü => ue... but than system skip parameters as not existing.

Does someone know how to encode UMLAUTS? I also confused is this HTTP GET issue or Solr issue.

Thanks for any help.

via user2960820