15.3 - https://www.progress.com/documentation/sitefinity-cms/for-developers-customize-the-lucene-search-scoring

CustomizedLuceneSearchService.cs

using Lucene.Net.Search;
using Telerik.Sitefinity.Services.Search.Data;
using Telerik.Sitefinity.Search;
using Lucene.Net.QueryParsers.Classic;
using System.Collections.Specialized;
using Telerik.Sitefinity.Configuration;
using Telerik.Sitefinity.Search.Configuration;
using Telerik.Sitefinity.Services.Search.Configuration;

namespace SitefinityWebApp.Documentation.Samples.Search
{
    public class CustomizedLuceneSearchService : LuceneSearchService
    {
        protected override Query BuildLuceneQuery(string compiledQuery, SearchOptions searchOptions, IndexSearcher searcher = null)
        {
            var parser = new QueryParser(Lucene.Net.Util.LuceneVersion.LUCENE_48, string.Empty, this.GetAnalyzer());
            parser.Locale = System.Globalization.CultureInfo.InvariantCulture;

            if (compiledQuery.Contains("*"))
            {
                if (searchOptions.SearchType == SearchType.Contains)
                {
                    parser.AllowLeadingWildcard = true;
                }

                parser.MultiTermRewriteMethod = WildcardQuery.SCORING_BOOLEAN_QUERY_REWRITE;
            }

            var query = parser.Parse(compiledQuery);
            if (searcher != null)
            {
                query = searcher.Rewrite(query);
            }

            bool excludeAge;
            var config = this.GetLuceneServiceConfig();
            bool.TryParse(config[LuceneSearchService.ExcludeContentAgeFromScoreCalculation], out excludeAge);
            return new SitefinityCustomScoreQuery(query, excludeAge);
        }

        private NameValueCollection GetLuceneServiceConfig()
        {
            var searchConfig = Config.Get<SearchConfig>();
            IConfigElementItem luceneService;
            if (searchConfig.SearchServices.TryGetItem(LuceneSearchService.ServiceName, out luceneService))
            {
                var parameters = ((SearchServiceSettings)luceneService.Element).Parameters;
                return parameters;
            }
            else
            {
                return new NameValueCollection();
            }
        }
    }
}