Help with Ruby code please (Using user input in searches)

puts "****************************************************"
puts "* This program will search Elastic Search Cloud    *"
puts "* based on a single field name and a single value  *"
puts "* for the given field name                         *"
puts "****************************************************"
puts
puts "Which field name in Elasticsearch would you like to search on?"
field_name = gets.chomp
#
puts "What value for [" + field_name + "] would you like to search for?"
field_value = gets.chomp
#
puts
puts "Searching for '" + field_value + "' in [" + field_name + "]"
puts
#######################################
# MAIN CODE BODY
#######################################
response = es.search index: 'filebeat-*',
                     scroll: '1m',
                     body: { 
                         query: {
                              bool: {
                                  must: [
                                      {match: { "event.id": "CLAPr91aCeIQsNNS04"}}
                                  ]
                              }
                         } 
                     }

Good Morning Everyone ... this code works just fine if I hard code the field and value in the match statement. For the life of me I cannot sort out how to get field_name and field_value (obtained from user input at the beginning of the code) inserted into the match statement ...

It's likely something super simple and I am just missing it ...

Appreciate any feedback ... thanks so much!