Query string query from javascript client

[yazhini_ravi]

Hi,
I am using elasticsearch 5.5 and my query is

"query":{
"query_string": {
"query": "state:MD AND city:Baltimore AND postalcode:12345"
}
}
This query works fine in kibana. But I use javascript API to execute the same query with user given values like

client.search({
index: 'sample',
type: 'data',
body:{
"query":{
"query_string": {
"query": "state:req.params.state AND city:req.params.city AND postalcode:req.params.pc"
}
}
}
}
})
In this code req.params.state, req.params.city and req.params.pc are user given values which are considered as value(string) itself and returns nothing because double quotes are used.So when I tried to remove double quotes the AND operater used is not validated as operator and thows an error.

I have used escaping characters but it doesnt work.Can anyone help me solve this problem?